<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>loading加载</title>
</head>
<body>
  <div style="font-size: 74px;padding: 45px 20px;color: #666;">
    我是内容区的文字啊  
  </div>
  <div class="loading">
    <div class="icon">加载中...</div>
  </div>
  <style>
    html,body{
      height: 100%;
    }
    body{
      margin: 0;
    }
    .loading{
      position: absolute;
      top: 0;
      right: 0;
      bottom: 0;
      left: 0;
      background: rgba(0,0,0,0.5);
    }
    .icon{
      width: 120px;
      line-height: 120px;
      text-align: center;
      margin: 50% auto;
      background: #fff;
      border-radius: 8px;
    }
  </style>
</body>
</html>